/*
    FreeRTOS Kernel V10.2.1
    Copyright (C) 2019 Amazon.com, Inc. or its affiliates.  All Rights Reserved.

    Permission is hereby granted, free of charge, to any person obtaining a copy of
    this software and associated documentation files (the "Software"), to deal in
    the Software without restriction, including without limitation the rights to
    use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
    the Software, and to permit persons to whom the Software is furnished to do so,
    subject to the following conditions:

    The above copyright notice and this permission notice shall be included in all
    copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
    FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
    COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
    IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
    CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

    http://www.FreeRTOS.org
    http://aws.amazon.com/freertos

    1 tab == 4 spaces!
*/

/*
    This is the list implementation used by the scheduler.  While it is tailored
    heavily for the schedulers needs, it is also available for use by
    application code.

    list_ts can only store pointers to list_item_ts.  Each ListItem_t contains a
    numeric value (xItemValue).  Most of the time the lists are sorted in
    descending item value order.

    Lists are created already containing one list item.  The value of this
    item is the maximum possible that can be stored, it is therefore always at
    the end of the list and acts as a marker.  The list member pxHead always
    points to this marker - even though it is at the tail of the list.  This
    is because the tail contains a wrap back pointer to the true head of
    the list.

    In addition to it's value, each list item contains a pointer to the next
    item in the list (pxNext), a pointer to the list it is in (pxContainer)
    and a pointer to back to the object that contains it.  These later two
    pointers are included for efficiency of list manipulation.  There is
    effectively a two way link between the object containing the list item and
    the list item itself.


    \page ListIntroduction List Implementation
    \ingroup FreeRTOSIntro
*/

#ifndef INC_FREERTOS_H
    #error FreeRTOS.h must be included before list.h
#endif

#ifndef LIST_H
#define LIST_H

/*
    The list structure members are modified from within interrupts, and therefore
    by rights should be declared volatile.  However, they are only modified in a
    functionally atomic way (within critical sections of with the scheduler
    suspended) and are either passed by reference into a function or indexed via
    a volatile variable.  Therefore, in all use cases tested so far, the volatile
    qualifier can be omitted in order to provide a moderate performance
    improvement without adversely affecting functional behaviour.  The assembly
    instructions generated by the IAR, ARM and GCC compilers when the respective
    compiler's options were set for maximum optimisation has been inspected and
    deemed to be as intended.  That said, as compiler technology advances, and
    especially if aggressive cross module optimisation is used (a use case that
    has not been exercised to any great extend) then it is feasible that the
    volatile qualifier will be needed for correct optimisation.  It is expected
    that a compiler removing essential code because, without the volatile
    qualifier on the list structure members and with aggressive cross module
    optimisation, the compiler deemed the code unnecessary will result in
    complete and obvious failure of the scheduler.  If this is ever experienced
    then the volatile qualifier can be inserted in the relevant places within the
    list structures by simply defining configLIST_VOLATILE to volatile in
    FreeRTOSConfig.h (as per the example at the bottom of this comment block).
    If configLIST_VOLATILE is not defined then the preprocessor directives below
    will simply #define configLIST_VOLATILE away completely.

    To use volatile list structure members then add the following line to
    FreeRTOSConfig.h (without the quotes):
    "#define configLIST_VOLATILE volatile"
*/
#ifndef configLIST_VOLATILE
    #define configLIST_VOLATILE
#endif /* configSUPPORT_CROSS_MODULE_OPTIMISATION */

#ifdef __cplusplus
extern "C" {
#endif

/*  Macros that can be used to place known values within the list structures,
    then check that the known values do not get corrupted during the execution of
    the application.   These may catch the list data structures being overwritten in
    memory.  They will not catch data errors caused by incorrect configuration or
    use of FreeRTOS.*/
#if( configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES == 0 )
/* Define the macros to do nothing. */
#define listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE
#define listSECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE
#define listFIRST_LIST_INTEGRITY_CHECK_VALUE
#define listSECOND_LIST_INTEGRITY_CHECK_VALUE
#define listSET_FIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem )
#define listSET_SECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem )
#define listSET_LIST_INTEGRITY_CHECK_1_VALUE( pxList )
#define listSET_LIST_INTEGRITY_CHECK_2_VALUE( pxList )
#define listTEST_LIST_ITEM_INTEGRITY( pxItem )
#define listTEST_LIST_INTEGRITY( pxList )
#else
/* Define macros that add new members into the list structures. */
#define listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE				TickType_t xListItemIntegrityValue1;
#define listSECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE				TickType_t xListItemIntegrityValue2;
#define listFIRST_LIST_INTEGRITY_CHECK_VALUE					TickType_t xListIntegrityValue1;
#define listSECOND_LIST_INTEGRITY_CHECK_VALUE					TickType_t xListIntegrityValue2;

/* Define macros that set the new structure members to known values. */
#define listSET_FIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem )		( pxItem )->xListItemIntegrityValue1 = pdINTEGRITY_CHECK_VALUE
#define listSET_SECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE( pxItem )	( pxItem )->xListItemIntegrityValue2 = pdINTEGRITY_CHECK_VALUE
#define listSET_LIST_INTEGRITY_CHECK_1_VALUE( pxList )		( pxList )->xListIntegrityValue1 = pdINTEGRITY_CHECK_VALUE
#define listSET_LIST_INTEGRITY_CHECK_2_VALUE( pxList )		( pxList )->xListIntegrityValue2 = pdINTEGRITY_CHECK_VALUE

/*  Define macros that will assert if one of the structure members does not
    contain its expected value. */
#define listTEST_LIST_ITEM_INTEGRITY( pxItem )		configASSERT( ( ( pxItem )->xListItemIntegrityValue1 == pdINTEGRITY_CHECK_VALUE ) && ( ( pxItem )->xListItemIntegrityValue2 == pdINTEGRITY_CHECK_VALUE ) )
#define listTEST_LIST_INTEGRITY( pxList )			configASSERT( ( ( pxList )->xListIntegrityValue1 == pdINTEGRITY_CHECK_VALUE ) && ( ( pxList )->xListIntegrityValue2 == pdINTEGRITY_CHECK_VALUE ) )
#endif /* configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES */


/*
    Definition of the only type of object that a list can contain.
*/
struct xLIST;
struct xLIST_ITEM {
    listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE			/*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
    configLIST_VOLATILE TickType_t
    xItemValue;			/*< The value being listed.  In most cases this is used to sort the list in descending order. */
    struct xLIST_ITEM* configLIST_VOLATILE pxNext;		/*< Pointer to the next ListItem_t in the list. */
    struct xLIST_ITEM* configLIST_VOLATILE pxPrevious;	/*< Pointer to the previous ListItem_t in the list. */
    void* pvOwner;										/*< Pointer to the object (normally a TCB) that contains the list item.  There is therefore a two way link between the object containing the list item and the list item itself. */
    struct xLIST* configLIST_VOLATILE pxContainer;		/*< Pointer to the list in which this list item is placed (if any). */
    listSECOND_LIST_ITEM_INTEGRITY_CHECK_VALUE			/*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
};
typedef struct xLIST_ITEM ListItem_t;					/* For some reason lint wants this as two separate definitions. */

struct xMINI_LIST_ITEM {
    listFIRST_LIST_ITEM_INTEGRITY_CHECK_VALUE			/*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
    configLIST_VOLATILE TickType_t xItemValue;
    struct xLIST_ITEM* configLIST_VOLATILE pxNext;
    struct xLIST_ITEM* configLIST_VOLATILE pxPrevious;
};
typedef struct xMINI_LIST_ITEM MiniListItem_t;

/*
    Definition of the type of queue used by the scheduler.
*/
typedef struct xLIST {
    listFIRST_LIST_INTEGRITY_CHECK_VALUE				/*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
    volatile UBaseType_t uxNumberOfItems;
    ListItem_t* configLIST_VOLATILE
    pxIndex;			/*< Used to walk through the list.  Points to the last item returned by a call to listGET_OWNER_OF_NEXT_ENTRY (). */
    MiniListItem_t
    xListEnd;							/*< List item that contains the maximum possible item value meaning it is always at the end of the list and is therefore used as a marker. */
    listSECOND_LIST_INTEGRITY_CHECK_VALUE				/*< Set to a known value if configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES is set to 1. */
} List_t;

/*
    Access macro to set the owner of a list item.  The owner of a list item
    is the object (usually a TCB) that contains the list item.

    \page listSET_LIST_ITEM_OWNER listSET_LIST_ITEM_OWNER
    \ingroup LinkedList
*/
#define listSET_LIST_ITEM_OWNER( pxListItem, pxOwner )		( ( pxListItem )->pvOwner = ( void * ) ( pxOwner ) )

/*
    Access macro to get the owner of a list item.  The owner of a list item
    is the object (usually a TCB) that contains the list item.

    \page listSET_LIST_ITEM_OWNER listSET_LIST_ITEM_OWNER
    \ingroup LinkedList
*/
#define listGET_LIST_ITEM_OWNER( pxListItem )	( ( pxListItem )->pvOwner )

/*
    Access macro to set the value of the list item.  In most cases the value is
    used to sort the list in descending order.

    \page listSET_LIST_ITEM_VALUE listSET_LIST_ITEM_VALUE
    \ingroup LinkedList
*/
#define listSET_LIST_ITEM_VALUE( pxListItem, xValue )	( ( pxListItem )->xItemValue = ( xValue ) )

/*
    Access macro to retrieve the value of the list item.  The value can
    represent anything - for example the priority of a task, or the time at
    which a task should be unblocked.

    \page listGET_LIST_ITEM_VALUE listGET_LIST_ITEM_VALUE
    \ingroup LinkedList
*/
#define listGET_LIST_ITEM_VALUE( pxListItem )	( ( pxListItem )->xItemValue )

/*
    Access macro to retrieve the value of the list item at the head of a given
    list.

    \page listGET_LIST_ITEM_VALUE listGET_LIST_ITEM_VALUE
    \ingroup LinkedList
*/
#define listGET_ITEM_VALUE_OF_HEAD_ENTRY( pxList )	( ( ( pxList )->xListEnd ).pxNext->xItemValue )

/*
    Return the list item at the head of the list.

    \page listGET_HEAD_ENTRY listGET_HEAD_ENTRY
    \ingroup LinkedList
*/
#define listGET_HEAD_ENTRY( pxList )	( ( ( pxList )->xListEnd ).pxNext )

/*
    Return the list item at the head of the list.

    \page listGET_NEXT listGET_NEXT
    \ingroup LinkedList
*/
#define listGET_NEXT( pxListItem )	( ( pxListItem )->pxNext )

/*
    Return the list item that marks the end of the list

    \page listGET_END_MARKER listGET_END_MARKER
    \ingroup LinkedList
*/
#define listGET_END_MARKER( pxList )	( ( ListItem_t const * ) ( &( ( pxList )->xListEnd ) ) )

/*
    Access macro to determine if a list contains any items.  The macro will
    only have the value true if the list is empty.

    \page listLIST_IS_EMPTY listLIST_IS_EMPTY
    \ingroup LinkedList
*/
#define listLIST_IS_EMPTY( pxList )	( ( ( pxList )->uxNumberOfItems == ( UBaseType_t ) 0 ) ? pdTRUE : pdFALSE )

/*
    Access macro to return the number of items in the list.
*/
#define listCURRENT_LIST_LENGTH( pxList )	( ( pxList )->uxNumberOfItems )

/*
    Access function to obtain the owner of the next entry in a list.

    The list member pxIndex is used to walk through a list.  Calling
    listGET_OWNER_OF_NEXT_ENTRY increments pxIndex to the next item in the list
    and returns that entry's pxOwner parameter.  Using multiple calls to this
    function it is therefore possible to move through every item contained in
    a list.

    The pxOwner parameter of a list item is a pointer to the object that owns
    the list item.  In the scheduler this is normally a task control block.
    The pxOwner parameter effectively creates a two way link between the list
    item and its owner.

    @param pxTCB pxTCB is set to the address of the owner of the next list item.
    @param pxList The list from which the next item owner is to be returned.

    \page listGET_OWNER_OF_NEXT_ENTRY listGET_OWNER_OF_NEXT_ENTRY
    \ingroup LinkedList
*/
#define listGET_OWNER_OF_NEXT_ENTRY( pxTCB, pxList )										\
    {																							\
        List_t * const pxConstList = ( pxList );													\
        /* Increment the index to the next item and return the item, ensuring */				\
        /* we don't return the marker used at the end of the list.  */							\
        ( pxConstList )->pxIndex = ( pxConstList )->pxIndex->pxNext;							\
        if( ( void * ) ( pxConstList )->pxIndex == ( void * ) &( ( pxConstList )->xListEnd ) )	\
        {																						\
            ( pxConstList )->pxIndex = ( pxConstList )->pxIndex->pxNext;						\
        }																						\
        ( pxTCB ) = ( pxConstList )->pxIndex->pvOwner;											\
    }


/*
    Access function to obtain the owner of the first entry in a list.  Lists
    are normally sorted in ascending item value order.

    This function returns the pxOwner member of the first item in the list.
    The pxOwner parameter of a list item is a pointer to the object that owns
    the list item.  In the scheduler this is normally a task control block.
    The pxOwner parameter effectively creates a two way link between the list
    item and its owner.

    @param pxList The list from which the owner of the head item is to be
    returned.

    \page listGET_OWNER_OF_HEAD_ENTRY listGET_OWNER_OF_HEAD_ENTRY
    \ingroup LinkedList
*/
#define listGET_OWNER_OF_HEAD_ENTRY( pxList )  ( (&( ( pxList )->xListEnd ))->pxNext->pvOwner )

/*
    Check to see if a list item is within a list.  The list item maintains a
    "container" pointer that points to the list it is in.  All this macro does
    is check to see if the container and the list match.

    @param pxList The list we want to know if the list item is within.
    @param pxListItem The list item we want to know if is in the list.
    @return pdTRUE if the list item is in the list, otherwise pdFALSE.
*/
#define listIS_CONTAINED_WITHIN( pxList, pxListItem ) ( ( ( pxListItem )->pxContainer == ( pxList ) ) ? ( pdTRUE ) : ( pdFALSE ) )

/*
    Return the list a list item is contained within (referenced from).

    @param pxListItem The list item being queried.
    @return A pointer to the List_t object that references the pxListItem
*/
#define listLIST_ITEM_CONTAINER( pxListItem ) ( ( pxListItem )->pxContainer )

/*
    This provides a crude means of knowing if a list has been initialised, as
    pxList->xListEnd.xItemValue is set to portMAX_DELAY by the vListInitialise()
    function.
*/
#define listLIST_IS_INITIALISED( pxList ) ( ( pxList )->xListEnd.xItemValue == portMAX_DELAY )

/*
    Must be called before a list is used!  This initialises all the members
    of the list structure and inserts the xListEnd item into the list as a
    marker to the back of the list.

    @param pxList Pointer to the list being initialised.

    \page vListInitialise vListInitialise
    \ingroup LinkedList
*/
void vListInitialise(List_t* const pxList) PRIVILEGED_FUNCTION;

/*
    Must be called before a list item is used.  This sets the list container to
    null so the item does not think that it is already contained in a list.

    @param pxItem Pointer to the list item being initialised.

    \page vListInitialiseItem vListInitialiseItem
    \ingroup LinkedList
*/
void vListInitialiseItem(ListItem_t* const pxItem) PRIVILEGED_FUNCTION;

/*
    Insert a list item into a list.  The item will be inserted into the list in
    a position determined by its item value (descending item value order).

    @param pxList The list into which the item is to be inserted.

    @param pxNewListItem The item that is to be placed in the list.

    \page vListInsert vListInsert
    \ingroup LinkedList
*/
void vListInsert(List_t* const pxList, ListItem_t* const pxNewListItem) PRIVILEGED_FUNCTION;

/*
    Insert a list item into a list.  The item will be inserted in a position
    such that it will be the last item within the list returned by multiple
    calls to listGET_OWNER_OF_NEXT_ENTRY.

    The list member pxIndex is used to walk through a list.  Calling
    listGET_OWNER_OF_NEXT_ENTRY increments pxIndex to the next item in the list.
    Placing an item in a list using vListInsertEnd effectively places the item
    in the list position pointed to by pxIndex.  This means that every other
    item within the list will be returned by listGET_OWNER_OF_NEXT_ENTRY before
    the pxIndex parameter again points to the item being inserted.

    @param pxList The list into which the item is to be inserted.

    @param pxNewListItem The list item to be inserted into the list.

    \page vListInsertEnd vListInsertEnd
    \ingroup LinkedList
*/
void vListInsertEnd(List_t* const pxList, ListItem_t* const pxNewListItem) PRIVILEGED_FUNCTION;

/*
    Remove an item from a list.  The list item has a pointer to the list that
    it is in, so only the list item need be passed into the function.

    @param uxListRemove The item to be removed.  The item will remove itself from
    the list pointed to by it's pxContainer parameter.

    @return The number of items that remain in the list after the list item has
    been removed.

    \page uxListRemove uxListRemove
    \ingroup LinkedList
*/
UBaseType_t uxListRemove(ListItem_t* const pxItemToRemove) PRIVILEGED_FUNCTION;

#ifdef __cplusplus
}
#endif

#endif

